1. Field of the Invention
The present invention relates to a drawing apparatus, an operation control method for a drawing apparatus, and a computer-readable recording medium storing an operation control program.
2. Description of the Related Art
Drawing apparatuses with a finger insertion portion have conventionally been suggested. A finger is inserted into the finger insertion portion so that its nail has a design drawn thereon.
Such a drawing apparatus needs to detect a region of a nail (nail region) of a finger for determining the printing range. For this purpose, a method has been known in which an image of a finger to be printed is acquired with a camera and the nail region is detected from the acquired image.
A technique for detecting the nail region is disclosed in, for example, JP-A-2012-146182 which employs the watershed method. The watershed method is one of the methods for dividing a region, in which the luminance gradient of the image is regarded as the ridgelines of a mountain and the image is divided into sections, each section being formed by the basin of the water flowing from the highpoints of the mountain (i.e., high-luminance positions).
According to JP-A-2012-146182, the nail region starts from the region with the highest luminance and the region including that start point is detected by the watershed method. This enables the extraction of the nail region from the image.
In general, however, a human nail includes a nail tip portion (portion apart from a nail bed portion) which seems whiter and has higher luminance than the other parts. For this reason, the detection of the nail tip portion has been difficult in the watershed method.